No it can't. When you open up a clock you see cogs and things moving. You can't observe time passing at all.
You can. But it's better to look at what a clock actually does, and then say that things move slower when the energy density is higher.
Time Explained
- Thread starter Dufoe
- Start date
What about bootstrap paradoxes? They are often used in sci-fi as a twist in the story.
http://en.wikipedia.org/wiki/Bootstrap_paradox
http://en.wikipedia.org/wiki/Bootstrap_paradox
True, but I said "in a conventional sense" which might be the same as "time seems to pass observationally".
How about this: Any event can be associated with an environment, and any environment can be called a system for purposes of thinking about it as a closed environment. Am I right, that is what we mean when we talk about a closed system, i.e. an environment that contains a specific content of matter and energy where the total energy density of the system remains fixed for talking purposes?
Place a clock, any clock, even a person can be a clock in this sense, in a given energy density environment and it will measure time consistent with that density.
Move the clock to another system with higher energy density, perhaps by accelerating the clock, and the rate at which it measures time will slow down and time will seem to be passing slower, when actually the cause of the slowing is that the clock is running slower because of the increased energy density.
Sorry eram, time travel is even more woo woo than gnat energy quanta.
The closet physical concept to time is entropy. Both time and entropy spontaneously move in one direction; time moves to the future, while entropy increases. The connection of time to entropy explains why time has to move forward. If you defined an entropy increase as related to increased randomness, then to go back in time would mean would need to reverse randomness back into order.
If we had firecracker blow up, into tiny paper fragments, a reverse of entropy would be analogous to all those paper fragments, smoke, particles and gases somehow coming back together into the firecracker. This could occur if we could reverse time.
The problem is when entropy reverses/decreases, such as liquid water freezing, there is energy given off; heat of fusion. But to reverse the firecracker and stick all the paper pieces together would not give off energy, but rather we would need to add energy. This extra added energy would not be 100% efficient, such that some of the energy would go into entropy and randomness; the past is not exactly the same. Therefore time could not be reversed 100%.
We can melt ice to increase entropy, with time moving forward. We can reverse the entropy of water by freezing it back into a solid ice; perfect crystal to liquid back to perfect crystal. But this will take energy through refrigeration. This refrigeration energy will increase entropy near the fridge, such that the original global state in time will be different. Time can only go one way and be entropy consistent.
If humans wanted to go back into time, it might be possible locally in an isolated way, but somewhere beyond the local, change due to entropy would occur. If our current self was to go back into time, we bring with us all the knowledge and experience of today. This past is not exactly the same past since we did not have those memories yet.
If we, instead, became the exact copy of what we were in the past, we would lose awareness of time traveling, since we did not know that in the past. A different path will also form because the physical universe will absorb the energy our time machine will need/generate, to increase the entropy of the past, for a different path to the future.
Conceptually, just as we can't predict the future due to entropy and randomness, we can't predict the exact past in time travel due to increase entropy and randomness due to the energy of the time machine.
If we had firecracker blow up, into tiny paper fragments, a reverse of entropy would be analogous to all those paper fragments, smoke, particles and gases somehow coming back together into the firecracker. This could occur if we could reverse time.
The problem is when entropy reverses/decreases, such as liquid water freezing, there is energy given off; heat of fusion. But to reverse the firecracker and stick all the paper pieces together would not give off energy, but rather we would need to add energy. This extra added energy would not be 100% efficient, such that some of the energy would go into entropy and randomness; the past is not exactly the same. Therefore time could not be reversed 100%.
We can melt ice to increase entropy, with time moving forward. We can reverse the entropy of water by freezing it back into a solid ice; perfect crystal to liquid back to perfect crystal. But this will take energy through refrigeration. This refrigeration energy will increase entropy near the fridge, such that the original global state in time will be different. Time can only go one way and be entropy consistent.
If humans wanted to go back into time, it might be possible locally in an isolated way, but somewhere beyond the local, change due to entropy would occur. If our current self was to go back into time, we bring with us all the knowledge and experience of today. This past is not exactly the same past since we did not have those memories yet.
If we, instead, became the exact copy of what we were in the past, we would lose awareness of time traveling, since we did not know that in the past. A different path will also form because the physical universe will absorb the energy our time machine will need/generate, to increase the entropy of the past, for a different path to the future.
Conceptually, just as we can't predict the future due to entropy and randomness, we can't predict the exact past in time travel due to increase entropy and randomness due to the energy of the time machine.
Your gnat energy quanta isn't woo, it's just "not even wrong."
Time travel isn't woo either, it's still stuck in the realm of sci-fi.
I love science fiction movies. A lot of them feature some kind of time travel, and I still love 'em. I can suspend my disbelief and happily eat my popcorn. But if you start thinking too hard about them, you start to see all the issues. Like near the end of the movie, it's all very exciting, and they have to move fast to save the world. They're in a hurry. Even though they've got a time machine. The bootstrap paradox is like that. It's just nonsense I'm afraid.
Time travel is woo. Time is just a cumulative measure of local motion through space. You can't travel through it.
I object, it IS wrong ... no wait, ... aw shucks :shrug:.
It's just a figure of speech. You and me can sit on my porch "passing the time". But I pass you a beer, not time. Then the beer passes your lips. Then a car passes down the road. Observationally, we see things move. Light moves, the Earth moves, electrochemical signals move in our brains, we move. Things move. Time doesn't.
Sure, no problem with that.
It will measure a thing you call time. But if it's a grandfather clock it's counting the swings of a pendulum. If it's a quartz wristwatch it's counting the vibrations of a crystal. No matter what sort of clock it is, it's counting some kind of regular cyclic internal motion and showing a cumulative display called "the time".
Which makes the regular internal cyclic motion go slower. That's it. That's all that happens. Imagine your clock is a parallel-mirror light clock and you place it where gravitational potential is low. It runs slower because...quantum wave said:
1911: If we call the velocity of light at the origin of co-ordinates cₒ, then the velocity of light c at a place with the gravitation potential Φ will be given by the relation c = cₒ(1 + Φ/c²).
1912: On the other hand I am of the view that the principle of the constancy of the velocity of light can be maintained only insofar as one restricts oneself to spatio-temporal regions of constant gravitational potential.
1913: I arrived at the result that the velocity of light is not to be regarded as independent of the gravitational potential. Thus the principle of the constancy of the velocity of light is incompatible with the equivalence hypothesis.
1915: the writer of these lines is of the opinion that the theory of relativity is still in need of generalization, in the sense that the principle of the constancy of the velocity of light is to be abandoned.
1916: In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when die Ausbreitungs-geschwindigkeit des Lichtes mit dem Orte variiert.
Understanding time is like pulling a thread with Einstein's name on it, and out comes a string of pearls.
Motor Daddy
Valued Senior Member
Time doesn't move, nor does entropy. Things move. When it comes to entropy, I thinks it's more fundamental to take the thermodynamical view rather than the statistical mechanics view. Available energy and the heat death of the universe and all that. Then entropy is reduced to sameness. See what quantum wave was saying about energy-density. When the energy density is the same everywhere, you can't do any work. All work does is even out the energy density a tad.
This could occur if we could reverse the motion that occurs and put everything back where it was.
You can't reverse it because there's no "forward" to it. Things move in all directions through space. They don't literally move forward through time.
Water molecules move, not time.
Take away energy from those water molecules and the water freezes. Just conduct your experiment in space and it will freeze all on its own. The energy radiates away into space.
You can't go back in time because you can't even go forward in time. You can go on a fast out-and-back trip through space and experience less local motion because of your macroscopic motion through space, total motion being limited to c. Or I can shove you in a gedanken freezer for a while, one where you thaw out hale and hearty. But you're always in my present, you never end up living a week ahead of me.
It's like every molecules, every atom, every electron, and every photon has been moved back to where it was.
There is no forward to time, no backward, and no path. it's like things move, sh*t happens, that's it.
There is no time travel, and there are no time machines.
All versions belong in the "Cesspool" section.
Thanks for the link, but I'm satisfied from our brief exchange that you understand energy density the same way I do as it relates to time.
You must be a cross between Frank Sinatra and Einstein.
Why Frank Sinatra?
Very interesting, and revealing if true, and I have no reason to doubt you. It only makes sense that he would understand that. So translate "die Ausbreitungs-geschwindigkeit des Lichtes mit dem Orte variiert".
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Exactly what I was thinking. The velocity of light is dependent on the energy density of the medium through which it passes, as if it was standing still and the energy environment around it was moving at difference velocities from every direction. Oh oh, maybe I went to far, lol.